(1) Field of the Invention
The invention relates to an electroluminescencet (EL) display, and more particularly to a design of the flexible printed circuit (FPC) extending to the organic EL structure.
(2) Description of the Prior Art
The organic electroluminescent display is characterized in high illumination, high reaction rate, lightness in weight, thinness, full color, and no need of backlight.
Please refer to FIG. 1, which is a side view of the organic EL display module 1. The organic EL display module 1 comprises a glass substrate 11, an organic EL structure 12, a package frame 13, and an FPC 14.
The organic EL structure 12, disposed under the glass substrate 11, further comprises an upper electrode, a lower electrode, and an organic multilayer structure having a hole injection layer, an active layer, and an electron injection layer (not shown in the figure). The upper and lower electrode can provide a bias voltage to the organic multiplayer, and electricity for activating the active layer is yielded after the electric hole and the electron combine in the active layer. The electricity activates the organic molecule of the active layer to an active state, and the light is released later on after the activated organic molecules discharge to fall back to a ground state.
Additionally, the upper electrode electrically connects to the FPC 14 via a bonding pad 111. The FPC 14 comprises a junction portion 141 and a main portion 142. As shown in FIG.1, the FPC 14 connects to the bonding pad 111 via its junction portion 141, and the main portion 142 extends along the direction leaving the organic EL structure 12. The FPC 14 can receive an image control signal from outer circuits to control the image display of the organic EL display module.
While assembling the organic EL display module described above into a product case (ex. a mobile phone), for the case space is limited and the FPC needs to protrude out of the the luminescent display, a bending process of the FPC is unavoidable. To reduce the possibility of damage from the bending process, a better material for the FPC, thus higher cost is required to suit the product application.
In the art, the interior space required for accommodating the bent FPC is one of crucial factors to determine the thickness of the product. Thus, how to minimize the thickness of the product without jeopardizing the reliability of the FPC is one of the issues that are deserved to be noticed.